karmada-scheduler-estimator add the support for custom DNS suffix

Signed-off-by: zhzhuang-zju <[email protected]>

pkg/estimator/client/cache.go

@@ -18,6 +18,7 @@ package client
 
 import (
 	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -108,20 +109,20 @@ func EstablishConnection(kubeClient kubernetes.Interface, serviceInfo SchedulerE
 		return nil
 	}
 
-	serverAddr, err := resolveCluster(kubeClient, serviceInfo.Namespace,
+	serverAddrs, err := resolveCluster(kubeClient, serviceInfo.Namespace,
 		names.GenerateEstimatorServiceName(serviceInfo.NamePrefix, serviceInfo.Name), int32(grpcConfig.TargetPort))
 	if err != nil {
 		return err
 	}
 
-	klog.Infof("Start dialing estimator server(%s) of cluster(%s).", serverAddr, serviceInfo.Name)
-	cc, err := grpcConfig.DialWithTimeOut(serverAddr, 5*time.Second)
+	klog.Infof("Start dialing estimator server(%s) of cluster(%s).", strings.Join(serverAddrs, ","), serviceInfo.Name)
+	cc, err := grpcConfig.DialWithTimeOut(serverAddrs, 5*time.Second)
 	if err != nil {
 		klog.Errorf("Failed to dial cluster(%s): %v.", serviceInfo.Name, err)
 		return err
 	}
 	c := estimatorservice.NewEstimatorClient(cc)
 	estimatorCache.AddCluster(serviceInfo.Name, cc, c)
-	klog.Infof("Connection with estimator server(%s) of cluster(%s) has been established.", serverAddr, serviceInfo.Name)
+	klog.Infof("Connection with estimator server(%s) of cluster(%s) has been established.", cc.Target(), serviceInfo.Name)
 	return nil
 }

pkg/estimator/client/service.go

@@ -31,37 +31,41 @@ import (
 // ResolveCluster parses Service resource content by itself.
 // Fixes Issue https://github.com/karmada-io/karmada/issues/2487
 // Modified from "k8s.io/apiserver/pkg/util/proxy/proxy.go:92 => func ResolveCluster"
-func resolveCluster(kubeClient kubernetes.Interface, namespace, id string, port int32) (string, error) {
+func resolveCluster(kubeClient kubernetes.Interface, namespace, id string, port int32) ([]string, error) {
 	svc, err := kubeClient.CoreV1().Services(namespace).Get(context.TODO(), id, metav1.GetOptions{})
 	if err != nil {
 		if apierrors.IsNotFound(err) {
 			/*
 			 * When Deploying Karmada in Host Kubernetes Cluster, the kubeClient will connect kube-apiserver
 			 * of Karmada Control Plane, rather than of host cluster.
 			 * But the Service resource is defined in Host Kubernetes Cluster. So we cannot get its content here.
-			 * The best thing we can do is just glue host:port together, and try to connect to it.
+			 * The best thing we can do is just assemble hosts and ports according to a specific rule, and try to connect to them.
 			 */
-			return net.JoinHostPort(fmt.Sprintf("%s.%s.svc.cluster.local", id, namespace), fmt.Sprintf("%d", port)), nil
+			return []string{
+				net.JoinHostPort(fmt.Sprintf("%s.%s.svc.cluster.local", id, namespace), fmt.Sprintf("%d", port)),
+				// To support the environment with a custom DNS suffix.
+				net.JoinHostPort(fmt.Sprintf("%s.%s.svc", id, namespace), fmt.Sprintf("%d", port)),
+			}, nil
 		}
 
-		return "", err
+		return nil, err
 	}
 
 	if svc.Spec.Type != corev1.ServiceTypeExternalName {
 		// We only support ExternalName type here.
 		// See discussions in PR: https://github.com/karmada-io/karmada/pull/2574#discussion_r979539389
-		return "", fmt.Errorf("unsupported service type %q", svc.Spec.Type)
+		return nil, fmt.Errorf("unsupported service type %q", svc.Spec.Type)
 	}
 
 	svcPort, err := findServicePort(svc, port)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	if svcPort.TargetPort.Type != intstr.Int {
-		return "", fmt.Errorf("ExternalName service type should have int target port, "+
+		return nil, fmt.Errorf("ExternalName service type should have int target port, "+
 			"current target port: %v", svcPort.TargetPort)
 	}
-	return net.JoinHostPort(svc.Spec.ExternalName, fmt.Sprintf("%d", svcPort.TargetPort.IntVal)), nil
+	return []string{net.JoinHostPort(svc.Spec.ExternalName, fmt.Sprintf("%d", svcPort.TargetPort.IntVal))}, nil
 }
 
 // findServicePort finds the service port by name or numerically.

pkg/estimator/client/service_test.go

@@ -18,6 +18,7 @@ package client
 
 import (
 	"context"
+	"reflect"
 	"testing"
 
 	corev1 "k8s.io/api/core/v1"
@@ -34,15 +35,15 @@ func TestResolveCluster(t *testing.T) {
 		port        int32
 		service     *corev1.Service
 		expectError bool
-		expected    string
+		expected    []string
 	}{
 		{
 			name:      "Service not found",
 			namespace: "default",
 			id:        "nonexistent",
 			port:      80,
 			service:   nil,
-			expected:  "nonexistent.default.svc.cluster.local:80",
+			expected:  []string{"nonexistent.default.svc.cluster.local:80", "nonexistent.default.svc:80"},
 		},
 		{
 			name:      "Unsupported service type",
@@ -81,7 +82,7 @@ func TestResolveCluster(t *testing.T) {
 					},
 				},
 			},
-			expected: "example.com:8080",
+			expected: []string{"example.com:8080"},
 		},
 		{
 			name:      "ExternalName service with non-int target port",
@@ -122,8 +123,8 @@ func TestResolveCluster(t *testing.T) {
 			if (err != nil) != tt.expectError {
 				t.Errorf("expected error: %v, got: %v", tt.expectError, err)
 			}
-			if result != tt.expected {
-				t.Errorf("expected: %s, got: %s", tt.expected, result)
+			if !reflect.DeepEqual(tt.expected, result) {
+				t.Errorf("expected: %v, got: %v", tt.expected, result)
 			}
 		})
 	}

pkg/util/grpcconnection/config.go

@@ -27,6 +27,7 @@ import (
 	"google.golang.org/grpc"
 	grpccredentials "google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 )
 
 // ServerConfig the config of GRPC server side.
@@ -99,11 +100,8 @@ func (s *ServerConfig) NewServer() (*grpc.Server, error) {
 	return grpc.NewServer(grpc.Creds(grpccredentials.NewTLS(config))), nil
 }
 
-// DialWithTimeOut creates a client connection to the given target.
-func (c *ClientConfig) DialWithTimeOut(path string, timeout time.Duration) (*grpc.ClientConn, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), timeout)
-	defer cancel()
-
+// DialWithTimeOut will attempt to create a client connection based on the given targets, one at a time, until a client connection is successfully established.
+func (c *ClientConfig) DialWithTimeOut(paths []string, timeout time.Duration) (*grpc.ClientConn, error) {
 	opts := []grpc.DialOption{
 		grpc.WithBlock(),
 	}
@@ -138,6 +136,25 @@ func (c *ClientConfig) DialWithTimeOut(path string, timeout time.Duration) (*grp
 	}
 
 	opts = append(opts, grpc.WithTransportCredentials(cred))
+
+	var cc *grpc.ClientConn
+	var err error
+	var allErrs []error
+	for _, path := range paths {
+		cc, err = createGRPCConnection(path, timeout, opts...)
+		if err == nil {
+			return cc, nil
+		}
+		allErrs = append(allErrs, err)
+	}
+
+	return nil, utilerrors.NewAggregate(allErrs)
+}
+
+func createGRPCConnection(path string, timeout time.Duration, opts ...grpc.DialOption) (conn *grpc.ClientConn, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
 	cc, err := grpc.DialContext(ctx, path, opts...)
 	if err != nil {
 		return nil, fmt.Errorf("dial %s error: %v", path, err)